Moonlight

Moonlight consists of mostly sunlight (with little earthlight) reflected from the parts of the Moon's surface where the Sun's light strikes.[1]

Holma Boat Club by the light of the moon
The Moon illuminates a boat club in Holma, Sweden.

Illumination

The intensity of moonlight varies greatly depending on its phase, but even the full Moon typically provides only about 0.05–0.1 lux illumination.[2] When the Moon is at perigee and viewed around upper culmination from the tropics, the illuminance can reach 0.32 lux.[2] The full Moon is only about one-millionth as bright as the Sun.

The color of moonlight, particularly around full moon, appears bluish to the human eye compared to most artificial light sources due to the Purkinje effect. Moonlight is not actually tinted blue, and although moonlight is often referred to as "silvery", it has no inherent silvery quality. The Moon's albedo is 0.136,[3] meaning only 13.6% of incident sunlight is reflected from the Moon. Moonlight generally hampers astronomical viewing, so astronomers usually avoid observing sessions around full Moon. It takes approximately 1.26 seconds for moonlight to reach Earth's surface.

Sunrise over the VLT

Moonlight shines on the Very Large Telescope.

Tonsvatnet, t%C3%A5ke og m%C3%A5ne

Moonlight illuminates a lake and surroundings.

Giftedtypist - red moon (by)

During a lunar eclipse, the Moon is colored red by indirect sunlight, which Earth's atmosphere has scattered and refracted.

Earthshine Moon

Earthlight (indirect sunlight reflected from Earth) illuminates the dim side of the Moon, while direct sunlight the bright side.

High ISO with long exposure

With manual exposure settings, photographs taken in moonlight do not appear much different from those taken in daylight.

Folklore

In folklore, moonlight sometimes has a harmful influence. For example, sleeping in the light of a full Moon on certain nights was said to transform a person into a werewolf. The light of the Moon was thought to worsen the symptoms of lunatics, and to sleep in moonlight could make one blind, or mad.[4] Nyctalopia (night blindness caused by a lack of vitamin A) was thought to be caused by sleeping in moonlight in the tropics.

"Moon blindness" is a name for equine recurrent uveitis. Moonlight is no longer thought of as the cause.

In the 16th century, moonmilk, a soft white limestone precipitate found in caves, was thought to be caused by the rays of the moon.[5]

Moonlight in art

Joseph Vernet - Night - Seaport by Moonlight - WGA24731

Seaport by Moonlight by Claude Joseph Vernet

Ed. Manet. Clair de lune sur le port de Boulogne

Clair de lune sur le port de Boulogne - Seaport of Boulogne by Moonlight by Édouard Manet

Visitor to moonlit churchyard

Visitor to a moonlit churchyard by Philip James de Loutherbourg

See also

References

  1. ^ Toomer, G. J. (December 1964). "Review: Ibn al-Haythams Weg zur Physik by Matthias Schramm". Isis. 55 (4): 463–465 [463–4]. doi:10.1086/349914.
  2. ^ a b Kyba, Christopher C M; Mohar, Andrej; Posch, Thomas (1 February 2017). "How bright is moonlight?". Astronomy & Geophysics. 58 (1): 1.31–1.32. doi:10.1093/astrogeo/atx025. Retrieved 14 February 2017.
  3. ^ Matthews, Grant (2008). "CERES". Applied Optics. 47 (27): 4981–93. Bibcode:2008ApOpt..47.4981M. doi:10.1364/AO.47.004981. PMID 18806861.
  4. ^ A Dictionary of English folklore, Oxford University Press, 2000
  5. ^ Gessner, Conrad (1555). Descriptio Montis Fracti sive Montis Pilati [Description of Mount Fractus, or Mount Pilatus] (in Latin). p. 54. Retrieved March 12, 2016.

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